This invention relates to a weighing apparatus and particularly, but not exclusively, to a portable weighing apparatus for weighing vehicles.
Portable weighing devices are known which can be placed under a wheel or wheels of a vehicle in order to measure individual wheel or axle loadings but such known devices generally utilize complicated load cells which are prone to failure, the devices are heavy and therefore not readily portable in the sense that they cannot easily be lifted and moved manually, and they are expensive to manufacture.
A mechanical load cell is known from U.K. Specification No. 1374316 which is used for determining the compression forces developed in mine supports, the cell comprising a solid body of compressible synthetic plastics material having an internal cavity filled with gas or liquid connected to an external indicator for indicating changes in pressure in the cavity when the body suffers changes in volume due to compression load, the body having secured thereto end pressure plates. Such a load cell cannot be used as a weighing device as any eccentric load applied to the plates would give a reading different to the same load when applied in the centre of the plates. In a weighing device it is essential for the reading to be accurate even if the load is applied eccentrically of the pressure plate.